The present invention relates to an apparatus for transmitting and receiving digital data, and more particularly to an apparatus for transmitting and receiving Manchester coded digital data for IEEE 802.3 Ethernet/Cheapernet type local area network.
As shown in FIG. 1, conventional transmitting and receiving apparatus in general utilize an isolated power supply 81 and a pulse transformer 82 to isolate both CS and CC terminals from the main circuit. However, the isolated power supply 81 and the pulse transformer 82 are quite bulky and expensive. Also, the total power consumption caused by the isolated power supply 81 is very significant. Moreover, in conventional apparatus, as shown in FIG. 1, a receiver 83 and a transmitter 84 are separated from a controller 85 by the isolated power supply 81 and the pulse transformer 82 such that both the receiver 83 and the transmitter 84 cannot be integrally formed with the controller 85 to produce a single chip. Therefore, the cost thus incurred cannot be reduced.
It is, therefore, the object of the present invention to obviate and mitigate the aforesaid drawbacks.